Vateria indica L. is an endemic arborescent recalcitrant tree species, native to the South-Western-Ghats of India. The natural regeneration process of the species is hindered by many factors including seed recalcitrance. Recently the species has been categorised as vulnerable since the population is fragmented and rapidly declining. Seed development is a highly complicated process which involves the interaction between phytohormones which regulate the process at different stages of morphogenesis. The orthodox seed development is marked by three distinct stages such as histodifferentiation, reserve accumulation and drying but in recalcitrant seeds, drying phase is absent. Recalcitrant seeds show marked differences from orthodox seeds in development. The onset of different stages is marked by a definite peaking and lowering of phytohormones and the hormonal pattern varies in orthodox and recalcitrant seeds. The present study was conducted to understand the interplay of phytohormones during embryogeny and the following natural embryo desiccation in the recalcitrant seeds of Vateria indica L. The present study revealed that the embryogeny and embryo drying in the recalcitrant seeds of Vateria indica L. shows a striking dissimilarity with the characteristic pattern of hormonal flux in orthodox seeds.
A pot experiment was carried out to evaluate the impact of plant growth regulators (PGRs) on translocation and accumulation of zinc (Zn) in grains of four wheat varieties of varying Zn sensitivities. Different concentrations of two (gibberellic acid and cytokinin) PGRs viz., control, 10 ppm gibberellic acid (GA), 20 ppm gibberellic acid (GA), 10 ppm cytokinin (kinetin), 20 ppm cytokinin (kinetin), 10 ppm gibberellic acid (GA) + cytokinin (kinetin), 20 ppm gibberellic acid (GA) + cytokinin (kinetin) were applied under different Zn regimes (control), soil application of 5 mg Zn kg-1 soil and soil application of 5 mg Zn kg-1 soil + foliar applications of 0.5% ZnSO4.7H2O + 0.25% lime). Four contrasting wheat varieties i.e., UP262 & PBW175 (Zn inefficient), UP2628 & UP2554 (Zn efficient); were tested for enzyme activities, yield attributes and Zn content in various plant parts. Regarding influence of PGR levels, the maximum CA and SOD activities were recorded under 20 ppm GA and control respectively. The grain yield, straw yield and grain Zn content was found to be the maximum under 10 ppm GA+cytokinin, 20 ppm GA and 20 ppm cytokinin respectively. Among all the methods used, soil along with foliar spray (Zn S+F) was found to be the most effective in improving all the crop parameters. Among varieties, the efficient sets of varieties (UP2628 & UP2554) performed better than Zn inefficient varieties. The use of plant growth regulators along with efficient delivery method could enhance the transport and accumulation of Zn in grains of wheat.
Use of resistant genotype is considered to be the most feasible means to mitigate sorghum grain damage by grain mold in a climate favourable for fungal invasion and subsequent mycotoxin contamination. Field-based experiments were conducted at Babile and Haramaya for two consecutive cropping seasons to evaluate 20 sorghum genotypes for their reaction to grain molds as well as aflatoxin and fumonisin contamination. Aspergillus flavus and Fusarium verticillioides with spore concentrations of 106 ml-1 were inoculated by spraying into the inflorescence, when the anther emerged from approximately 50–70% of the spikelets. Mycotoxin analysis was done using enzyme-linked immunosorbent assay (ELISA). The results revealed that the sorghum genotypes evaluated for their reactions to A. flavus and F. verticillioides inoculation had significantly different responses. Variety Melkam was identified as a susceptible genotype to F. verticillioides and variety Birhan was found resistant to both fungal species. Variety Long Muyera was the most susceptible to both toxigenic fungi. Long Muyera was contaminated with aflatoxin B1 and total fumonisin above the maximum tolerable limit of 10 µg kg-1 and 2000 µg kg-1, respectively. Though the sorghum genotype Birhan was resistant to A. flavus, its aflatoxin B1 contamination was relatively high. In this study, it was recognized that none of the tested sorghum genotypes exhibited possession of multiple resistance to the inoculated toxigenic fungi. Therefore, it is commendable to select and use genotypes, which are resistant to specific toxigenic fungi for a particular location, where the problem exists.
Chickpea (Cicer arietinum), one of the major pulse crops in India, endured extreme reduction in production due to various abiotic and biotic stresses. Endophytic bacteria residing in the nodules and roots of chickpea plants enable host in combating these stresses. Twenty one endophytic bacteria isolated from nodules and roots of chickpea were screened for multiple plant growth promoting traits like ammonia, organic acid, siderophore, hydrogen cyanide (HCN) and phytohormone indole acetic acid (IAA) production. Out of these, 86% isolates produced ammonia, around 50% isolates produced organic acid, HCN and siderophore, 29% isolates produced ACC (1-aminocyclopropane-1-carboxylic acid) deaminase, while only 14% isolates solubilized phosphate. Interestingly, all the isolates were able to produce IAA ranging from 11.6–85.2 μg/ml, isolate CPJN 13 being the maximum IAA producer (85.5±2.33 μg/ml). Isolate CPJN13 was selected for IAA optimization studies. The yield of IAA increased up to 4 fold i.e. 331±4.96 μg/ml at optimized conditions. IAA production was also confirmed by TLC and HPLC analysis of crude IAA extract. The application of CPJN13 on chickpea seedlings resulted in significant increase in plant growth parameters. The 16S rDNA sequencing of CPJN13 revealed its similarity with Pseudomonas lini strain and submitted to NCBI with accession number MF574502. To best of our knowledge, this is the first report of the presence of P. lini as endophyte in chickpea nodules. The results of this study imply that the endophytic P. lini has a potential role to enhance the plant growth.
Nanosized titanium dioxide (nTiO2) is one of the most diverse nanomaterials available today but inconclusive studies on the effects of nTiO2 on plants are withholding its successful application in agriculture. In the present work, an attempt has been made to evaluate the interaction of nTiO2 with Vigna radiata (L.) Wilczek from the seed germination stage until the plants were 14 days old. TEM analysis revealed that nTiO2 was synthesized in the size range of 1–10 nm and X-ray diffraction (XRD) analysis confirmed the crystal structure. The plants were raised hydroponically in nutrient solution spiked with two different concentrations of nTiO2 (10 and 100 mg L−1). Inductively coupled plasma mass spectrometry (ICP-MS) results established the accumulation of nTiO2 in leaves. In response to the presence of nTiO2, V. radiata plants performed better as indicated by their increased seed germination, root and shoot length, higher fresh and dry weight and elevated chlorophyll and flavonoid contents. Germination percentage of V. radiata seeds increased by about 22% at 10 mg L−1 and 14% at 100 mg L−1 nTiO2 concentration. Maximum stimulation of total chlorophyll, flavonoids and phenolic contents was observed at 100 mg L−1 nTiO2 concentration in 7-day old plants, where an astonishing 8 fold increase in chlorophyll, 3 fold increase in flavonoids and 2 fold increase in phenolics was observed. However, a decrease in carbohydrate and protein contents and an increase in lipid peroxidation also marked the presence of mild oxidative stress that was neutralized by increased activity of antioxdant enzymes namely catalase, glutathione reductase and glutathione-s-transferase. The activity of superoxide dismutase was more or less stable while glutathione peroxidase activity reduced compared to the control plants. The higher ABTS and DPPH free radical scavenging activities of the nTiO2 treated plants also supported effective neutralization of free radicals.
Mungbean (Vigna radiata L. Wilczek) an important legume crop with valuable nutritional and health benefits is severely affected by drought conditions. Desiccation tolerance is a capacity of seeds to survive and maintain physiological activities during storage and stress conditions. LEA proteins are group of stress associated proteins that help the plants survive water deficit stress. Here we have performed genome-wide analysis of mungbean LEA (VrLEA) genes, and also insilico physical/functional characterization. Gene-positioning showed that 307 VrLEAs are present in all the eleven chromosomes, but are unevenly distributed.Upstream promoter sequence analysis of LEA genes revealed the occurrence of MYB transcription factor (TF)in higher number compared to other TFs i.e., bZIP, AP2, WRKY, NAC and bHLH.Further, we downstreamed our analysis to fewer VrLEAs, based on drought responsive data. The VrLEAs obtained from the earlier experimental data were examined for its organelle localization and found that they are intracellular functional proteins.
The monitoring of xylogenesis makes it possible to follow tree growth responses to stress factors in real-time, by observing the course of wood cell division and differentiation. Proper microscopy techniques are of key importance to exactly identify the xylem cells during the different phases of differentiation. We aimed to apply epifluorescence microscopy to follow the lignification process during the different phases of xylogenesis in Mediterranean softwood and hardwood. Microcores from trees of Pinus halepensis Mill. and Arbutus unedo L. were collected at a site in southern Italy, during the period June-December. Fluorescence imaging of sections stained with a water solution of safranin and Astra blue clearly highlighted the contrast between lignified and un-lignified tissue. The proposed methodology is useful to quickly and unambiguously detect the different stages of cell differentiation, as well as the progress in the lignification process. Moreover, it proved to be easily applied to demanding wood materials, such as Mediterranean woods and can be helpful to better track stress responses and the development of anomalies during wood formation, such as intra-annual density fluctuations.
Structural differences in the secondary vascular tissues among habitats can contribute to understanding species performances, especially regarding water and photosynthate transport. The pattern of association between the secondary xylem tissue and water availability from the environment has been widely studied, unlike the secondary phloem, which has been barely explored. Here, we evaluated the structural variation of the secondary xylem and phloem in stems of four populations of two tropical tree species under contrasting water conditions. We also investigated the mirrored structure between both tissues. At dry sites, Moquiniastrum polymorphum had higher vessel density, thicker xylem fibers cell walls, and taller rays in both tissues commonly associated with safe transport, in agreement with our expectations. In contrast, the populations of Zanthoxylum rhoifolium had most features in disagreement with the water availability of each site. The perforation and sieve plates, the ray composition, and the axial parenchyma were similar in the two tree species’ xylem and phloem tissues. However, the quantitative descriptors of cell sizes were not correlated between the xylem and phloem. In general, there is a different pattern of morphological variation across sites in the two tropical tree species, highlighting that any generalization regarding the vascular system structure across environments should be avoided. Xylem and phloem revealed a mirrored structure in a few qualitative features, not followed by the dimensions of different cell types. Future research needs to explore the causes of the unexpected structural variation in the vascular system across populations in tropical tree species.
Branch canker disease caused by the fungus Macrophoma theicola is a major stem disease that reduces the yield of south Indian tea plantations. Hence the present study aimed to assess the efficacy of the biocontrol agent Trichoderma spp against various isolates of Macrophoma spp. For this matter, different tea-growing regions of south India were surveyed for the isolation and characterization of Macrophoma spp. Then, fungal biocontrol strains (Trichoderma viride, Trichoderma atroviride, Trichoderma harzianum, and Gliocladium virens) were procured from microbial type culture collection Centre (MTCC) to screen their antagonistic potential on different isolates Macrophoma spp. The spores of Macrophoma spp were examined through a light microscope and identified by their peculiar morphological features such as non-septum pycnidiospores present in the sac and oval shape spore with stalk and confirmed using 18S rRNA gene sequence. The results revealed that the biocontrol G. virens followed by T. harzianum showed a higher inhibitory effect on different isolates of Macrophoma spp in the dual plate and culture filtrate studies. In the well diffusion method, the fungal biocontrol agents were found to be exhibit non-significant differences on different isolates of branch canker pathogen. The hyphal interactions studies showed that the pathogenic hyphal wall shrunk and penetrated by the interaction of G. virens.
We describe two new fossil woods from the San Carlos Formation (Upper Cretaceous), Chihuahua State, Mexico. The first wood resembles the fossil genus Metcalfeoxylon in having solitary vessels, scalariform perforation plates, vessel-ray parenchyma pits of similar size as the intervessel pits, axial parenchyma apotracheal diffuse and diffuse in aggregates, and heterocellular multiseriate rays with long, uniseriate tails. The second wood is a new fossil genus, and it is characterized by having diffuse porous wood, vessels predominantly solitary, vessel outlines oval and tending to be of two diameter classes, simple perforation plates, minute alternate intervessel pits, vessel-ray parenchyma pits similar to intervessel pits in size and shape, vasicentric tracheids, non-septate fibers, homocellular rays, and exclusively uniseriate and biseriate rays. This combination of features supports its placement in Myrtales (?Myrtaceae), in a new fossil-genus named Lazarocardenasoxylon. These two new records provide more information about the floristic composition of the Late Cretaceous flora of the San Carlos Formation and its relationship with those from the southern USA. However, a definitive picture of the floristic relationship of these Cretaceous floras of northern Mexico and southern USA remains elusive.